I thought people here might be interested to read my article on the company that brought us the Kepex gate and the Gain Brain limiter in the early 1970's.... Allison Research. The Kepex/Gain Brain combo became "the sound of drums" in the 70's and beyond. They went on to become Valley People, also known for the Dyna-mite.
Anyway, if you're like me and crazy about vintage studio gear, you might find it a good read.

I've also scanned and uploaded 11 original Allison documents, including brochures, manuals and even 2 price lists from 1970 and 1971!
There's even a little youtube video of Gain Brains in action at my studio in Sydney